The invention pertains to acoustic detectors, and in particular those used as medical diagnostic instruments.
Many anatomical processes create turbulence, and hence generate characteristic acoustic signals, an example of which is an intersaccular aneurysm which results from the wall of an intracranial artery becoming dangerously weakened. Under normal systolic pressure, such a weakened arterial wall distends exaggeratedly, generating in the surrounding fluid and soft tissue acoustic waves having a bandwidth and temporal shape characteristic of the aneurysmal condition. Because the consequences of a ruptured aneurysm can be so drastic, and because aneurysms are often asymptomatic until rupture, any device that can detect and identify these characteristic acoustic signals would be most welcome. Unfortunately, the skull, being very rigid compared to surrounding fluid and soft tissues, constitutes both a damping and reflective barrier for such signals. Consequently, any detection system that attempts to detect acoustic signals after they have traversed the skull will inherently have a poor signal to noise ratio and poor sensitivity.